During the past year studies were conducted in several areas related to male reproduction. A detailed histological study of the chimpanzee epididymis was completed. That study complements other studies directed to localization of the site of production of epidiymal specific, androgen dependent proteins with potential contraceptive application. Immunohistochemical studies chimpanzee epididymal protein EP-1 were initiated using anti-EP-1 antibodies generated in rabbits to identify the sites of synthesis, secretion and absorption of EP-1 within the chimpanzee epididymis. Antibodies against chimpanzee epididymal protein EP-2 were generated using chickens. Those antibodies will be used in both biochemical and immunohistochemical studies to identify the sites of synthesis, secretion and absorption of EP-2 within the chimpanzee epididymis. Rhesus macaque males were androgen deprived to confirm the androgen independence of EP-1 and androgen dependence of EP-2. The EP-2 homolog in the rhesus monkey was cloned. The rhesus EP-2 message exhibits a much more complex pattern of alternative splicing than does the message in the human or chimpanzee. There are at least 6 major splicing isoforms of EP-2 RNA identified thus far. Furthermore, since use of different sets of exons leads to shifts in the reading frame, the proteins encoded by these RNA isoforms can differ greatly, to the point where only a few amino acids are common to any two proteins. Experiments have commenced to prepare subclones of the different EP-2 splicing isoforms suitable use in DNA vaccination in the rhesus monkey (male and female), to test whether antibodies generated in situ against the EP-2 peptides lead to inactivation of those peptides with resulting infertility in the animal.